The invention relates to a nonvolatile memory cell.
There are materials that have at least two distinct stable resistivity states. This class of materials can be switched from a high-resistivity state to a low-resistivity state by applying a voltage magnitude across the material in a first direction. To switch the material from the low-resistivity state back to a high-resistivity state, the voltage magnitude can be reversed.
Some of these materials can be switched between resistivity states at relatively low applied voltages, for example two volts or less, and preferably one volt or less. These properties would make these materials attractive for use in nonvolatile memory arrays, which retain their memory state even when power is removed from the device. Low-voltage switching is advantageous to reduce power consumption in devices, but many challenges must be overcome to provide the low voltages and reversible voltages required to operate cells incorporating such material, and to avoid accidental change of state during read or during the writing of other cells in a large array of cells.